Each year, 6.2 million extremity fractures are treated in the US at a cost in excess of $13 billion. Even today, 5-8% of these fractures experience complications in fixation and healing, which presents a significant secondary, but preventable, public health issue. Locked plating is thought to be one of the most important, present-day advancements in fracture fixation. It preserves periosteal blood supply and may improve fixation in osteoporotic bone. As such, it provides a tremendous opportunity to improve the healing rate in problematic high-energy fractures and osteoporotic fractures alike. By providing a potential solution to a pressing clinical challenge, locked plating technology has gained rapid and widespread acceptance despite the virtual absence of supportive data. This enthusiasm is in stark contrast to the 13-21% failure rates found in recent clinical reports on locked plates. The majority of these clinical complications manifest as delayed unions or non-unions. The likely reason for these complications is the high stiffness of locked plate constructs, which can suppress the interfragmentary motion required for secondary bone healing. Unlike conventional plates, locked plates rely on secondary bone healing by callus formation. As a solution to this problem inherent to locked plating, we have explored a novel strategy, termed Far Cortical Locking (FCL), capable of reducing the stiffness of locked plate constructs while retaining sufficient fixation strength. The proposed in vivo study will investigate for the first time, how locked plating affects fracture healing in an ovine fracture model. In addition, we will test if stiffness-reduced FCL fixation can enhance fracture healing. Specific Aim 1 will compare periosteum-sparing locked plating and conventional plating to determine if biology-preserving locked plates can improve fracture healing. Specific Aim 2 will compare locked plating and FCL plating to determine if stiffness-reduced FCL constructs can improve fracture healing. Specific Aim 3 will compare FCL plating to standard conventional plating to evaluate the combined benefit of biology-preservation and reduced stiffness provided by FCL plating. This proposed exploratory and developmental research constitutes an urgent first step toward evaluation and optimization of locked plating technology on a scientific basis. Results will have direct clinical implications by providing a long-overdue evaluation of readily adopted locked plating technology. Furthermore, results may direct the future evolution of locked plate technology by providing a working solution to an inherent problem associated with contemporary locked plates. [unreadable] [unreadable] [unreadable]